Context and motivations:
When an aircraft goes through a rain event, water droplets are deposited on the windshield. After coalescing, they form larger single drops, which can evolve into continuous films or rivulets. The accumulation of liquid water can degrade the pilot's visibility. According to the wetting properties of the window surface, this loss of visibility depends on the capacity of the water to flow under the effect of aerodynamic forces. For several years, numerical tools have been developed to study the dynamics of water runback on a wall subjected to an aerodynamic shear stress for different types of structures: continuous films, rivulets and isolated drops. For the case of an isolated drop on a wall, the modeling of the aerodynamic driving force represents a major difficulty. Indeed, in the case of a high Reynolds number aerodynamic flow with the development of a boundary layer on the wall, the size of the droplet compared to the local thickness of the boundary layer determines the estimation of the aerodynamic force.

Objectives:
The objective of the internship is to characterize the gas flow around a drop on a wall, in order to estimate the aerodynamic force exerted on the drop as a function of the local aerodynamic parameters and the geometrical parameters of the drop (in particular the ratio Rdrop/delta where Rdrop is the radius of the drop and delta the local thickness of the boundary layer). To do this, the student will use the OpenFOAM computational tool to estimate the aerodynamic forces acting on the drop. A simplified modeling of the aerodynamic force will be proposed using a reduced number of parameters describing the boundary layer, the drop, and its position in the boundary layer.

Skills required:
Master student with a strong interest in numerical simulation.